Indication means for light signals



Apr. 3,. 1923. 1,450,548

L. F. HOWARD INDICATION MEANS FOR LIGHT SIGNALS ori inal Filed Mar. 2, 1921 a INVENTOR: 7C WW,

wa cw H w ATTORNEY I 10 type comprising lamps,

20 is known as an indication device? 50 two electrical lamps Patented Apr. 3, 1923.

1,450,548" NITED STATES PATENT ornca L'EMUEL F. HOWARD, F EDGEWObD BOROUGH, PENNSYLVANIA, ASSIGNOR TO THE UNION SWITCH & SIGNAL COMPANY, OF SWISSVALE, PENNSYLVANIA, A COB/P0- BATION PENNSYLVANIA.

INDICATION MEANS FOR LIGHT SIGNALS.

ori inal application and March 2,

1921, Serial No. 449,144. Patent No. 1,429,141, dated September 12,

1922. Divided and this'application filed August 11, 1922. Serial No. 581,101.

To all whom it may concern:

Be it known that I, LEMUEL F. HOWARD, a citizen of the United States, residin at Edgewood Borough, in the county of Hegheny and State of Pennsylvania, have invented certain new and useful Im rovements in Indication Means for Light ignals,;of

which the following is a specification.

My invention relates to signals of the and has for an obect the provision of means for indicating illumination of the lamp at a point remote from. the lamp.

Apparatus embodying my invention is particularly well adapted for use in connection with railway signals which are con trolled by the levers of interlocking machines. In systems of this character the lever is usually provided with a lock wlgch ne feature of my invention is the provision of means for controlling this lock in accordance with the light which is actually emit- 1 ted by one of the lamps in the signal governed by such lever.

The present application is a division of 10 my co-pending application filed on the 2nd day ofMarch, 1921, indication means for light signals now Patent No. 1,429,141, Sept. 12, 1922.

I will describe two forms of apparatus embodying my invention, and will then point out the novel features thereof in claims. V

In the accompanying drawings, Fig. 1 is a diagrammatic view showing oneform of apparatus embodying my invention, the lever lock being controlled directly by a light responsive cell which is exposed to the light' from one of the signal lamps. Fig. 2 is a view showing a modification of the ap-' paratus shown in Fig. 1, the lever lock in this instance being controlled by a relay which in turn isgoverned by thelight responsive cell.

Similar reference characters refer to similar parts in each of the views. Referring first to Fig. 1, the reference character S designates, a signal comprising G and R, which lamps when illuminated are adapted to. indicate proceed and stop, respectively. Theselamps are at times supplied with current Serial No. 44.9144. for

from the secondary 2 of a transformer T,

suitable source which is not shown in the drawing.

The supply of current to the signal lamps Gr and R. is controlled by a contact 41 which is attached to lever A, and which engages with a contact 5 or with a contactv 5, according as the lever is in one position or another. .As shown in the drawing, the lever A is in the right hand extreme position wherein contact 45 is closed. Lamp G is then supplied with current through a circuit-which passes from the right hand terminal of transformer secondary 2, through wire 7, contact 45 wire 8, lamp G, and wires 9, 10 and 11 to transformer secondary 2. l/Vhen the lever A is shifted to the left,

.the stoplamp R becomes illuminated by virtue of a circuit which passes from transformer secondary 2, throu h wire 7 contact 4-5, wire 12, lamp and wires 13,

and 11 to secondary 2.

The lever A will usually be one of a plurality of similar levers in an interlocking machine, and, as is well understood, in apparatus of this nature the various levers are usually inter-controlled by what is known as fmechanical locking. For this reason it is desirable that a complete movement of the lever A to its extreme left hand position should be prevented until an indication is given at the lever that the stop lamp R has become illuminated. To accomplish this the lever is provided with a lock or indication device B comprising a shoulder 15 on the lever, a dog 14 normally in position toengage with this shoulder, and a magnet 16 arranged when energized to lift the dog 14 out of the path of the shoulder 15. The parts are so proportioned that when the lever is shifted to the left the shoulder 15 engages the dog 14 after contact i 5 is the extreme left' hand position The magnet 16 of the lever lock B isconthat its electrical resistance varies in accordance with changes in the intensity of the light to which it is exposed. A cell having this characteristic may be made, for example, of selenium, stibnite, or cop-per oxide, or may be what is known as a photoelectric cell in which the active material is an alkali metal. The precise nature of this cell and the substance of which it is composed, form no part of my present invention. The only essential feature of construction is that this cell shall be so located as to receive light from the lamp R but not from any other source.

The magnet 16 is controlled by the cell F through the medium of a VVheatstone bridge organization. Two legs of the bridge are in the form of resistances 50 and 51, while the other two legs are the cell F and a resistance 10 respectively. The source of current is a secondary 3 on transformer T, which secondary is connected with points 52 and 53, while the bridge member is the winding of magnet 16 which is connected with points 54 and 55, this winding taking the place of the galvanometer which is generally used in connection with the Wheatstone bridge network of circuits. The parts a of the apparatus may be so adjusted that when the cell F is dark there is no current supplied to the-winding 16. lVhen the cell F is illuminated, however, the electromotive forces are unbalanced, so that current then flows in winding 16. As is well understood, the apparatus Ina be so designed that a comparatively sma 1 change in resistance of the cell F will cause a comparatively large amount of current to flow through the magnet winding 16.

It follows that when the stop lamp R isdark, magnet 16 is de-energized so that the movement ot lever A cannot be completed, but that when lamp R is lighted, so that the resistance of cell F is decreased, the current which is then supplied to magnet 16 is suiiicient to elevate the dog 14, so that the movement of lever A to its left hand extreme position may be completed.

If desired, a visual indicator may be provided at the lever A to show the operator whether the lamp G or the lamp R of signal S is illuminated. This indicator,'as here shown, comprises two incandescent lamps G and R, which are supplied with current from the transformer secondary 2, through a contact 21 which is operated by the armature or" magnet 16. When signal lamp G is illuminated, the contact 21 is in its lowest position, so that current is supplied to indicator lamp Gr through wires 7 and 20, con-- tact 21, lamp G and wires 22 and 11 to transformer secondary 2. When signal lamp R becomes illuminated, the consequent elevation of the armature of magnet 16 raises contact 21 to its highest position mamas 27, 29 and 30 to secondary 3. finding 23 of relay Q is controlled by cell F in the same manner as magnet 16 in Fig. 1. That is to say, this winding constitutes the bridge member of a VVheatstone bridge the four legs of which are resistances 50, 51 and 40 and the cell F. Relay Q and the circuit-s associated with its windings are so designed and proportioned that' when the cell F is dark, contact 37 is open, but that when the cell F is exposed to light rays from the lamp R this contact 37 is closed. As is well understood, the relay Q may be so designed that thegreater part of the energy required for operating this relay is furnished by the winding 2et and that winding 23 need supply only a comparatively small amount of controlling energy. It follows that the light responsive cell F need carry only a comparatively small amount of current, and that this current can be considerably weaker than the current which must be transmitted through the cell F in Fig. 1.

Magnet 16 is controlled by contact 37 of relay Q, the circuit for this magnet being from transformer secondary 3, through wires 25, 31 and 36, contact 37, wire 38, mag net 16 and wires 39 and 30 to secondary 3.

The operation of the apparatus shown in Fig. 2 will be apparent from the foregoing without further explanation. If desired, a visual indicator may be provided at the lever A, and as here shown, this indicator comprises two lamps, G and B; These lamps are controlled by an additional contact 21, operated by relay Q. The circuit for these lamps is from transformer sec-,

ondary 3, through wires 25, and 41, lamp G or R, contact 21, and wires 12, 29 and 30 to secondary 3. It will be apparent that indicator lamp G will be illuminated when signal lamp G is illuminated, and that similarly the indicator lamp R will be illuminated when the signal lamp R is illuminated.

- prisinga lamp,

Having thus described. my invention, what I I claim is:

1. In combination,

a cell exposed to the light emitted by said'lamp and having the characteristic of varying in electrical resistance with variations in the intensity of light to which it is exposed, a lever for'controlling the illumination of said lamp, governing said lever, a Wheatstone bridge having sald cell for one leg, and means 1ncluded in. the bridge member of said bridge for controlling said lever lock.

with variations 'in' 2. In combination, a railway signal comprising a lam a cell exposed to the light lamp andhaving the char.- acteristic of varying in electrical resistance which it is'expos'ed, a-lever for controlling the illumination of said lamp, a lock for governing said lever, a Wheatstonebridge having said cell for one leg, and a magnet included in the bridge member of said bridge and adapted when energized to releasesaid lock.

" '3. In combination, a railway signal comprising a lamp, a cell exposed to the light emitted by said lamp and having the characteristic of varying in electrical resistance, with variations in the intensity of light to which it is exposed, a lever for controlling the illumination of said lamp, a lock for governing said lever, a" Wheatstone bridge having sald cell for one leg, a relay comprising two windings one of which is included in the bridge member of other of which is supplied with current independently of said cell, and means gova railway signal coma lock for the intensity of light .to a

bridge having said cell for one leg,

said bridge and the erned by said relay for controlling; said lever lock. 1

4. In combination, a railway signal comprising a lamp, a cell exposed to'the light emitted by saidlamp and having the characteristic of varying in with variations in the intensity of light to which it is exposed, a Wheatstone bridge having said cellfor one leg, and means for indicating illumination of said lamp at a distant point comprising a winding included inthe bridge member of said bridge.

. 5. In combination, prising a lamp, a cell exposed to the light emitted by said acteristic of varying in electrical resistance with variations in, the intensity of light to which it is exposed, a Wheatstone bridge having said cell for one leg, a relay having two windings one of which is included in the bridge member of said bridge and the other of which is supplied with current in-' dependently of said cell, and means contion of said lamp at a distant: point.

6. In combination, a railway signal comprisinga lamp, acellexposed to the light emitted by said lamp and. having the characteristic of varying in electrical resistance with variations in the intensity of light to which it is exposed, a lever for controlling the illumination of said lamp, a Wheatstone and means controlled the bridge member of. said bridge for overning said lever.

In testimony w er'eof I aflix my signature.

LEMUEUF: HOWARD.

electrical resistance a railway signal comlamp andhaving the char- I 

